Fall Bright Chinook Salmon
Fall-bright chinook, as their name implies, retain their "bright" silvery ocean color for weeks after entering fresh water. Spawning males turn dark green with rose-pink flanks. Females may have a duller version of the males' colors, but some acquire a brassy sheen. All races of chinook can be distinguished from other salmon by their gray gums and their tail fins, which have spots on both lobes.
Fall chinook typically spend 3 ½ to 4 ½ years at sea, returning to frest water as 4-5 year olds. In August and September fall chinook migrate upriver, sometimes swimming 60 miles in a day. They spawn in October and November.
Fall brights are presently the most abundant salmon in the Columbia River Basin, and numbers have been slowly increasing since the mid-1960s. This is mainly due to hatchery production, since little natural spawning habitat is left. Historically many fall chinook used to spawn in the main river stem, and most of this habitat has been altered by dams.
Spring Chinook Salmon
When they first arrive in fresh water, spring chinook are greenish with paler flanks. As spawning approaches they become grayer and darker; spawning males can almost be black. Their bodies are slender and rounded in cross-section, whereas fall chinook are more slab-sided; this allows spring chinook to swim more easily in turbulent, fast-flowing water.
Spring chinook spend 1-5 years at sea. They migrate upriver from March to May and stay in fresh water for weeks or months before they are ready to spawn. Unlike fall chinook, spring chinook prefer to spawn in smaller rivers and side streams. Spring chinook fry spend over a year living in fresh water, and are aggressive to others of their kind.
Spring chinook used to outnumber fall chinook in Columbia River catches 2 to 1, but this is no longer the case. Because their fry spend a long time living in streams, spring chinook have been especially hard-hit by pollution and siltation of stream habitat. Upriver stocksthose that have to pass through several damsare very low. Lower river stocks have increased since the 1950s, mainly due to hatchery production.